Who said there is a shrinking demand for large, powerful SUVs? Not BMW, that's for sure. The German powerhouse has started extreme durability testing on the new twin-turbo V8-powered BMW X5 in the southwestern part of the United States.

The sort of testing that might have once been conducted in the Northern Territory (no longer viable due to speed limits) takes full advantage of the local hot temperatures, kilometres of desert roadways and mountains with steep grades.

The X5's twin-turbo engine is shared with the X6. The 4.4-litre V8 is expected to have about 300kW and roughly 610Nm of torque.

The twin-turbo will be unveiled in the US later this year. As for availability in Australia, BMW has been contacted for comment.